The concept of a document is central to many business operations. A document may be defined as a writing (printed or displayed) which conveys information. Documents are typically created, stored and manipulated in a computing environment using a word processing software application, such as WordPerfect or Microsoft Word. The word processing application interacts with an underlying operating system, such as OS/2, DOS or Windows in personal computing environments. Word processing and operating systems also exist for midrange and mainframe computing environments.
Documents containing mathematical computations are also central to many business operations. For example, a loan agreement with a financial institution may include the computation of a monthly payment based upon data for the loan amount, interest rate, and number of payments.
Spreadsheets are used in a variety of business applications for performing mathematical computations. A spreadsheet presents a blank form on which numerical, statistical, financial or other data can be assimilated, organized, manipulated, and calculated. A typical spreadsheet software application, such as Lotus 1-2-3, comprises an array of columns and rows. The intersection of each column and row is a "cell" in which a value, formula, or label may be entered and computations performed.
It is often desirable to incorporate computations and information generated from a spreadsheet and other information entities directly into a document, referred to as a compound document. Compound documents combine into a single container the results of data processing performed by various external applications, typically using text to explain the relationships between the incorporated data.
To meet this need for compound documents, vendors have designed mechanisms for linking objects, such as spreadsheets, with a document. For example, Microsoft Object Linking and Embedding (OLE) allows customized links to be created between certain applications and a document using proprietary linking techniques. The linking techniques utilized by OLE are described in chapters 1, 8, and 9 of Inside OLE 2: The Fast Track to Building Powerful Object-Oriented Applications with Windows Objects, by Kraig Brockschmidt, published by Microsoft Press, 1993.
Other customized linking systems are described in U.S. Pat. No. 5,235,701 to Ohler et al. entitled "Method of Generating and Accessing a Database Independent of Its Structure and Syntax"; U.S. Pat. No. 5,263,167 to Conner, Jr. et al. entitled "User Interface for a Relational Database Using a Task Object for Defining Search Queries in Response to a Profile Object Which Describes User Proficiency"; and U.K. Patent Application GB-2 242 293 A to Heninger entitled "Apparatus and Method for Dynamic Linking of Computer Software Components".
However, linking a spreadsheet with a document has several disadvantages. One disadvantage involves the inherent positional constraints of spreadsheets. Because cells within a spreadsheet are indexed by position, it may not be possible to link individual cells of a spreadsheet with a document. In order to incorporate a computation generated by a spreadsheet, the entire spreadsheet may need to be linked with the document. Consequently, space within a document may be occupied by a spreadsheet having many cells containing nothing at all. Furthermore, if computations need to be located in different portions of a document, a spreadsheet may need to be linked with the document at each location, causing further inefficient use of document space.
Yet another disadvantage in linking a spreadsheet with a document is that existing linking techniques of this nature do not facilitate refreshing the data contained within the linked object. It is often desired to incorporate the latest data into a document rather than old data. However, it may be difficult to perform or update computations contained within the spreadsheet from within the document. In particular, in order to perform the mathematical operations to refresh the data, it may be necessary to bring up the spreadsheet application program, run the computations, and generate an updated spreadsheet. Thus, there is a need to provide a mechanism for refreshing computational data linked with a document without requiring the launching of a separate software application program.